Engines, including diesel engines, gasoline engines, and gaseous fuel-powered engines are used to generate a mechanical, hydraulic, or electrical power output. In order to accomplish this power generation, an engine typically combusts a fuel/air mixture. This combustion process generates large amounts of heat and, in order to ensure proper and efficient operation of the engine, a cooling system is required to cool fluids directed into or out of the engine.
An internal combustion engine is generally fluidly connected to several different liquid-to-air and/or air-to air heat exchangers to cool both liquids and gases circulated throughout the engine. These heat exchangers are often located close together and/or close to the engine to conserve space on the machine. An engine-driven fan is disposed either in front of the engine/exchanger package to blow air across the exchangers and the engine, or between the exchangers and the engine to draw air past the exchangers and blow air past the engine.
The size of the engine, power output of the engine, and/or exhaust emissions from the engine may be at least partially dependent on the amount of cooling provided to the engine. That is, the engine may have a maximum temperature and a most efficient operating temperature range, and operation of the engine may be limited by the ability of the associated exchangers to maintain the engine's temperatures below the maximum limit and within the optimum range.
One way to maintain the engine's temperatures within an optimal range is disclosed in U.S. Pat. No. 6,904,875 (the '875 patent) issued to Kilter on Jun. 14, 2005. The '875 patent describes a coolant circuit of an internal combustion engine. The coolant circuit includes a coolant pump, coolant temperature sensors, and a bypass valve that routes coolant flow from the internal combustion engine, depending on its position, through a radiator or passing the radiator to the coolant pump. The bypass valve is electronically controlled to route a greater or lesser coolant flow through the radiator in response to signals from the temperature sensors such that an optimal range of engine temperatures is maintained. That is, in control of the coolant temperature within the circuit, the position of the bypass valve is regulated as a function of the coolant temperature at the outlet of the internal combustion engine and by the difference between the coolant temperatures at the outlet and the inlet of the internal combustion engine.
Although the coolant circuit of the '875 patent may help to maintain desired coolant temperatures, it may be complex and limited. Specifically, the coolant circuit utilizes multiple temperatures sensors and requires complex calculations to control the bypass valve. The multiple sensors increase hardware cost and complexity, while the multiple inputs and calculations increases control difficulty. Further, because control of the bypass valve is based primarily on engine outlet temperature, the inlet temperature experienced by the engine and having the greatest effect on engine operation may be insufficiently controlled. Further, the coolant circuit of the '875 patent may be inapplicable to an engine system having dual coolant circuits interrelated by way of primary and secondary aftercoolers.
The disclosed cooling system is directed to overcoming one or more of the problems set forth above.